Among structures of this sort, there is one that guides fluid to a pressure receiving surface of a diaphragm to detect a displacement of the diaphragm, and converts the displacement into pressure to measure the pressure of the fluid.
Such a structure is also used to measure the pressure of a liquid containing air bubbles, and therefore as described in Patent Literature 1, a flow type structure is known that makes air bubbles less likely to accumulate by flowing fluid in from a first flow path vertical to a diaphragm, and flowing the fluid out from a second flow path, which branches from the first flow path.
Meanwhile, in this structure, the fluid flowing through the first flow path vertically hits against the diaphragm such that the diaphragm may be bent by the kinetic energy of the fluid beyond a bent level caused by the pressure of the fluid, and therefore a measurement error may occur.
For this reason, to develop the present invention, the present inventor has designed an intermediate structure that is, as illustrated in FIG. 3, provided with a base, a diaphragm, and an internal space formed between the base and the diaphragm, and is also provided with: a protruding part that protrudes from the base toward the internal space; a first flow path that extends from a bottom surface side of the base toward the diaphragm; and a second flow path that is formed from a fore end part of the first flow path orthogonally to the first flow path, and opens on an outer lateral surface of the protruding part.
According to such a configuration, fluid is introduced into the internal space from the opening formed on the outer lateral surface of the protruding part, and flows toward a peripheral wall of the internal space, and therefore the fluid can be prevented from vertically hitting against the diaphragm.
However, in order to form the above-described flow paths, a step of forming the flow paths in two directions, i.e., a vertical direction vertical to the diaphragm and a horizontal direction orthogonal to the vertical direction, is required, and therefore working hours and processing cost for the step are incurred.